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H. P. KIRKPATRICK-PICARD'Sv H. THAME. METHOD OP MANUFACTURING ELEMENTS OR'PLATBS POR SECONDARY BATTERIES.

No. 527,861. Patented Oct. 23,1894.

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UNTTnD STATES PATENT Ornticn.'

HUGH FITZALIS KlRKPATRlCK-PICARD AND HENRY THAME, OF LONDON,

ENGLAND.

METHOD OF MANUFACTURING ELEMENTS OR PLATES FOR SECONDARY BATTERIES.

SPECIFICATION forming part of Letters Patent No. 527,861, dated October 23, 1 894.

Application filed LTanuary lO, 1894.v

To all whom it may concern:

Beit known that we, HUGH FITzALIs KIRK- PArRIcK-PIOARD and HENRY THAME, both residing at London, England, have invented an Improved Method of Manufacture of Elements or Platesfor Secondary Batteries, of which the following is a specification.

Our invention relates to an improved method of manufacture of elements or plates for secondary batteries, and has for its object the production of an element or plate, of which the body is of a finely crystalline and strong salt of lead, namely a sub-sulphide of lead, artificially prepared as hereinafter described, and though eventually becoming more porous by elimination of sulphur, is durable, and where desired is homogeneously and metallically connected to an upper rim or portion of a rim of lead, on which a pole piece may be formed with perfect metallic continuity from the body of the plate or element.

TVe are aware that many attempts have been made to produce a compound plate or battery element of lead and salts of lead, in which the salts such as lead sulphide have been packed within a supporting frame of lead, but such crushed, packed, lead sulphide has proved too rotten, under subsequent electrical action, to stand alone, and such plates have not attained the above objects for which our improved manufacture has been devised.

To carry our invention into effect we use a metallic mold, of which the internal walls are first lubricated by some suitable material, such as talc, chalk, or graphite (which last material is that we most prefer).

In order that our invention may be the better understood, we herewith illustrate and describe the appliances by which we carry out our method of manufacture of said elements for secondary batteries.

Figure l is a half sectional elevation and Fig. 2,- a'transverse section of a double metallic mold for the purpose of forming the plates. Figs. 3 and 4l are an outside elevation and transverse section through a; y of the completed element and pole piece attached.

The mold is formed of an inner plate A with a projecting ridge B on each side outlining the form of the element of plate to be cast, and having a throat O and vent holes D D by Serial No. 496.432. (No specimens.)

which the molten metal may be poured and the displaced air or gases escape. Outer plates E E are bolted on the said inner plateV to form the mold. The pole rim of metallic lead F is first poured in the bottom of the molds. When the plate is cast and cooled, the leaden pole piece G is dovetailed into the leaden pole rim F and the joint is covered completely by gutta percha or vulcanite H. Feet of Vulcanite K are then dovetailed upon the bottom of the plate on which the plate may rest when placed in the battery.

VVe'heat the mold, and gates of the mold, to prevent the chilling'of the molten material when poured into the mold, and to maintain the molten condition of a first charge of lead to form apole rim, until the body of the plate has formed a homogeneous and metallic attachment thereto. The mold is preferably placed in a vertical position, and a suitable amount of metallic lead is poured into the bottom of the mold to form a pole rim, on which a pole piece can be afterward burned. When a complete lead pole rim is not needed, we have found thatour plate, made as described above, is so strong and durable, that a part rim, or a piece restricted to a corner, is sufficient for the attachment of the pole piece, and the plate is sufficiently durable and homogeneous to enable us to cut out a piece of the plate, cast withouta lead pole rim, and to burn in a pole piece. 'While the said lead pole-rim, where used, is still molten, the body of the element or plate, prepared as hereinafter described, is poured into the mold, and on cooling, the salt of the body of the plate is found to be finely crystalline in structure, and though even somewhat porous now by crystallization,and afterward still more porous by elimination of the sulphur, to be strong, durable, and self-supporting without a frame, and also to be homogeneously and metallically connected to the lead pole rim.

The body of the plate`l or element is prepared as follows:-We melt galena in one crucible, and metallic lead in another crucible, raising them to about the same temperature. We then mix the molten lead and galena together, preferably in about equal weight for negative plates, but with a lower percentage of galena up to say twenty per TOD cent. for positive plates. This is most conveniently done by pouring the lead slowly, and from a considerable height, into the crucible containing the molten galena, and the mixture, which thus becomes an artificial sub-sulphide of lead, and is inely crystalline on cooling, and homogeneous, is poured into a heated metallic mold, to form a plate or element. A

The plate may be cast in any desired form, either flat, corrugated, cylindrical, or in any convenient shape.

If it is thought desirable, the plate may be submitted to a roasting process, to oxidize the lead salt forming the body of the plate, means being taken to protect the lead pole rim from excessive or oxidizing heat.

These plates may, after having been prepared by our above described method of manufacture, be submitted to any suitable Vulcanizing process, to insulate them from one another and the cell; or feet of vulcanite or other insulating material may be fitted into the under side of the plate. The plates are now ready to be put into cells, and formed by any suitable method.

Having now described our invention, what We claim, and desire to secure by Letters Patent, is-

1. A method of manufacture of elements or plates for secondary batteries, consisting of melting separately galena and metallic lead, mixing the same, and pouring the mixture in a molten condition into a heated metallic mold, substantially as described.

2. An element or plate for secondary batteries, composed Wholly as to its operative body of lead sub-sulphide as described from a mixture of molten lead and galena, manufactured substantially as and for the purpose herein described.

3. In the manufacture of elements or plates for secondary batteries, the placing of a molten lead pole rim or portion of a rim at the bottom of a heated mold, and pouring thereon a molten mixture of metallic lead and galena, to form a homogeneous plate, substantially as described.

et. An element or plate for secondary batteries consisting as to its operative body of lead sub sulphide, and as to one end or portion of one end ot a pole rim of metallic lead homogeneouslyand metallically connected to the said body, substantially as described.

In testimony whereof We have signed our names to this specification in the presence of two subscribing Witnesses. l Y

HUGH FITZALIS KlRKPA'lRlCK-PICARD. HENRY THAME. Witnesses:

RICHARD A. HOFFMANN, CHARLES H. CARTER. 

